gistfile1.js

//First way
Promise.resolve(userModel.findOneAndUpdate({uid: myUserId}, updatedUserModel, {
        upsert: true,
        "new": false
    }).exec())
        .then(function (user) {
            ...
        })
        .spread(function markNotificationsAsRead(unreadNotifications) {
            ...
 
        })
        .then(function sendResponse(unreadNotifications) {
            ...
        })
        .then(null, function (err) {
            //handle error
        });
 
//Second way
userModel.findOneAndUpdate({uid: myUserId}, updatedUserModel, {
        upsert: true,
        "new": false
    }).exec()
        .then(function (user) {
            ...
        })
        .spread(function markNotificationsAsRead(unreadNotifications) {
            ...
 
        })
        .then(function sendResponse(unreadNotifications) {
            ...
        })
        .then(null, function (err) {
            //handle error
        });